<template>
  <div>
    <div class="item"></div>
  </div>
</template>

<script>
export default {
  data() {
    return {};
  },
  methods: {},
};
</script>
<style scoped>
.item {
  position: fixed;
  top: 0;
  bottom: 0;
  width: 100px;
  height: 100px;
  border: 1px solid black;
  background: red;
}
</style>